The present invention relates to a method for stabilizing a woven, knitted or other cloth, an apparatus for stabilizing the same, and a method for manufacturing the same.
A woven, knitted or other cloth for a sewing purpose undergoes a number of processes such as spinning, weaving or knitting, degumming, breaching, dying, and so on, before becoming the final product. During these processes, an individual fiber or yarn is forced to stretch or shrink. Part of the stretch or shrinkage appears as permanent dimensional change whereas the rest stays latent within the cloth as residual strain. When sewn, if the cloth is moistened or heated for ironing or thermally bonding an interlining cloth, then the residual strain is released, appearing as dimensional change, namely stretch and/or shrinkage, often resulting in a wrinkle or distortion in the cloth.
A reason for this is presumably that the moisture, heat and so on make inside of the cloth lubricated and swollen, promoting interaction among different forces such as partial release of the internal stress of the fiber, change in molecular movement, change in molecular cluster structure, change in fiber aggregate structure and so on, allowing the fiber or the yarn to return to a state of stabilization. In order to eliminate the stretch and shrinkage during or after the sewing process, a variety of dimension stabilizing treatments are performed before the interlining-cloth bonding process or the sewing process.
For example, a sponging treatment disclosed in the Japanese Patent Laid-Open No. 6-228858 is one of the dimension stabilizing treatments mentioned above. The sponging treatment has been a mainstream of the dimension stabilizing treatments for a variety of cloths.
The sponging treatment disclosed in the above gazette is a combination of steaming treatment and steam-pressing treatment, and is considered to reduce an amount of dimensional change such as shrinkage and stretch during the interlining-cloth bonding process and intermediate/finish pressing process.
In the interlining-cloth bonding process, in which the stretch and shrinkage of the cloth is most intense, the cloth and the interlining cloth are heated up to about 130xc2x0 C. in general so as to melt a thermally plastic binder on an bonding boundary surface. Thereafter, the cloth and the interlining cloth are pressed to bond together.
In recent years, with an increasing diversity in the cloth material, there is an increasing diversity in weaving structure and so on. Further, density of the cloth often varies from place to place. For these reasons, it is difficult to heat an entire cloth uniformly.
In such a case as above, in order to attain a guaranteed lowest temperature of a surface to be bonded with the interlining cloth, temperature of the heater is often increased. However, if the temperature of the heater is increased, inconsistency develops in heating temperature, and the cloth near the heater is subjected to a high temperature, which often exceeds 150xc2x0 C.
Under such a temperature condition as above, the cloth develops significant stretch and/or shrinkage even after the sponging treatment as disclosed in the above gazette. Thus, the cloth must be pre-cut in an over size, and then re-cut into a desired size after the interlining cloth is bonded. This leads to a problem that a significantly increased number of steps must be necessary.
Even if the interlining cloth is not bonded, the cloth is often finish-pressed or ironed at a temperature of 140xc2x0 C. or higher. If the cloth is subjected to such a high temperature even for a short time, the cloth develops significant shrinkage and/or stretch even after treated by the prior art sponging treatment, often resulting in a product with flaw such as a wrinkle.
Further, in the conventional stabilizing apparatus as described above, the cloth which is like a long ribbon is wound around a number of rollers while each of the steps as described above is performed. This means that the operations are made to the cloth which is under tension, and dimension stabilizing effect cannot be achieved sufficiently.
It is therefore an object of the present invention to provide a method for stabilizing the cloth, an apparatus for stabilizing the cloth, and a method for manufacturing the cloth capable of solving the above problems, thereby stabilizing the size of the cloth to be bonded with the interlining cloth, to be finish-pressed or otherwise treated, as well as eliminating the development of the wrinkle and so on.
A method for stabilizing cloth according to the present invention comprises a moisture controlling step of adding water to the cloth, and a thermal pressing step of pressing the water-added cloth under heat, and further, each of the steps is performed while the cloth is supported on a belt running horizontally.
Generally, when the interlining cloth is thermally bonded in the interlining-cloth bonding process, pressing operation is usually performed under dry and hot condition. Further, in order to make sure that the entire surface to bond to the interlining cloth is maintained at a temperature higher than a melting temperature of the thermally plastic binder, the whole cloth is maintained at a high temperature for a predetermined time and then the pressing is made by a roller. Therefore, a surface of the cloth near the heater is subjected to thermal load greater than a temperature necessary for the bonding. The inventor of the present invention discovered that during the interlining-cloth bonding process or the finish-pressing process after sewing, the surface of the cloth is subjected to a temperature much higher than the temperature applied in the conventional sponging treatment and so on, and the pressing operation is performed under this high temperature. Another finding was that during these steps, moisture in the cloth is significantly reduced from a normal amount contained under temperature and humidity conditions of a room where the cloth is being treated.
The inventor of the present invention confirmed that if the cloth is pre-treated under conditions reflecting the temperature and humidity used in the above interlining-cloth bonding process and so on, the cloth does not overly stretch or shrink even when the interlining-cloth bonding process is performed by heating the whole cloth at a temperature higher than 150xc2x0 C., and came to the invention of a method for stabilizing cloth according to the present application.
By adding moisture, it becomes possible to reduce friction thereby increase lubrication among fibers or yarns of the cloth. Further, it becomes possible to prevent damage to the texture of the cloth and deterioration in mechanical characteristics of the cloth caused by a high thermal load applied in a thermal pressing step to be described later. The moisture controlling step can be performed by spraying water to the cloth, or spraying steam from a boiler for example, to the cloth.
If no moisture is added, thermal conductivity decreases, making difficult to stabilize the cloth, increasing possibility for damage to the cloth when the cloth is heated to a temperature necessary for the stabilization.
There is no specific limitation to an amount of moisture to be added; however, it is preferable to allow the cloth to contain an amount of moisture at least greater than normally contained therein at a temperature of a room where the stabilization is performed. If the amount of moisture is less than normally contained, the cloth may be damaged when heated. In order to obtain dimension stabilizing effect, the amount of moisture to be added should be 5% or less of a weight of the cloth under the normal condition. Further, the effect can be expected in most of the cloths by adding 2% through 4% of moisture.
The cloth stretches/shrinks when added with even a small amount of moisture. Therefore, even the moisture controlling step is performed while supporting the cloth on a belt running horizontally, making sure that no extra stress is caused in the cloth.
In the thermal pressing step, the cloth added with water is pressed under heat. In order to obtain desired dimension stabilizing effect, it is preferable to heat at least a region to be pressed, to a uniform temperature before applying pressure.
According to the present invention, the moisture added in the moisture controlling step covers up the entire cloth in the form of steam, and therefore the cloth can be heated uniformly. Further, when temperature of the cloth increases, the moisture serves as a lubricant, enabling efficient release of the internal stress of the cloth.
The reason why the dimensional stability of the cloth can be obtained by performing the thermal pressing is not clearly known yet. However, it is presumed that a structure of the cloth under the heated state is fixed by the pressure applied in the pressing operation. The stabilization prevents excessive shrinkage of the cloth, while increasing smoothness of cloth surfaces, making easy to handle the cloth in the processes to follow.
In order to obtain the above dimension stabilizing effect, it is important that each of the operations is made on a horizontal plane in which the cloth is not subjected to tension. According to the conventional sponging treatment apparatus, the cloth is wound around a cylindrical roller at least in one step of the treating process. Therefore, the treatment is made while the cloth is under tension caused by the roller or by the weight of the cloth itself. The tension leaves latent stress in the cloth, which is released at the time of thermal bonding process, often causing the dimensional change, wrinkles and so on
According to the present invention, the entire process of the cloth stabilization treatment is performed while the cloth is supported horizontally, and therefore the cloth is supported horizontally, and therefore the cloth is not subject to tension or other force caused for example by the weight of the cloth itself. Further, no deformation is caused by curved surfaces of the rollers. Thus, the cloth can be sufficiently stabilized.
In order to stabilize the cloth more reliably, it is preferable to include a temperature-holding step of heating the cloth and maintaining a temperature of the cloth between an upper and a lower non-gas-permeable belts running horizontally, without causing tension, before the thermal pressing step. In the temperature-holding step, the water added in the moisture controlling step is first vaporized to cover up the entire cloth and then the temperature continues to increase. Further, by heating the cloth between the non-gas-permeable belts, the entire cloth can be heated more uniformly, with smaller amount of water added. Still further, the heating is made in a state in which the cloth is supported free of tension, allowing the cloth to freely shrink for example, enabling sufficient release of the internal stress of the cloth.
Further, even if heating means such as a heater has a fairly high surface temperature, non-uniform heating will not result, allowing the entire cloth to be heated to a predetermined temperature in a short time. A temperature in the temperature-holding step through the thermal pressing step is preferably 130xc2x0 C.xcx9c180xc2x0 C.
Dimensional change of the cloth is a problem when the interlining cloth is bonded. Temperature for this operation is determined from a melting temperature of the binder which is made from a thermally plastic resin, and is about 130xc2x0 C. in general. If the heating temperature is not greater than a thermal-bonding temperature, the cloth is often stretched and/or shrunken at a temperature used in the interlining-cloth bonding process. Therefore, the heating temperature should be higher than the thermal-bonding temperature, or at least not lower than 130xc2x0 C. Further, preferably, the heating should be performed at a temperature at least 10 degrees higher than the thermal-bonding temperature. By treating at the temperature higher than the temperature used in the thermal bonding, the dimensional stability in the thermal bonding process can be more stable and reliable. Still further, the temperature should be higher by more than 15xc2x0 C. if the cloth has appropriate heat resistance.
On the other hand, the temperature not lower than 180xc2x0 C. is not preferred because texture of the cloth is lost although the stabilization of the cloth is achieved.
Further, a temperature of 150xc2x0 C.xcx9c170xc2x0 C. can also be used in the finish-pressing process. Therefore, in order to stabilize the cloth in the finish-pressing process, the heating temperature should preferably be higher than the finish-pressing temperature.
Preferably, a pressure for the thermal pressing step is 0.02 kg/cm2xcx9c3 kg/cm2. The pressure may be changed depending on the kind, thickness and so on of the cloth, but should be selected in a range in which wrinkles formed in previous steps can be removed, texture of the cloth is not be deteriorated, and desired thermal treatment effect can be rendered. If the pressure is smaller than 0.02 kg/cm2, the wrinkles in the cloth may not be removed. On the other hand, if the pressure is greater than 3 kg/cm2, the cloth may be flattened and texture of the cloth may be deteriorated. In order to reliably stabilize the cloth as well as to smoothly remove the wrinkles etc., the pressure may be gradually increased in the thermal pressing step.
In the temperature-holding step through the thermal pressing step, the weight of the cloth is preferably reduced to 98xcx9c90% of the normal weight of the cloth. In the interlining-cloth bonding process or the finish-presing process, the weight of the cloth is significantly reduced from the normal weight since the cloth is subjected to a high temperature. The above rate of weight reduction was selected with respect to a corresponding weight reduction rate in the interlining-cloth bonding process through the finish-presing process. The reason why the cloth can be stabilized if heated until its normal weight is lost is not clearly known yet. However, it is presumed that the thermal treatment effect is so reliably retained that a similarly high temperature applied thereafter will not easily cause dimensional change etc.
If the temperature and the time for the heating is selected within the range given above, not only is the dimensional stabilization effect of the cloth obtained but also the cloth is protected from excessive loss of the water contained therein. Therefore, it becomes possible to stabilize the cloth without deteriorating the texture of the cloth or deteriorating mechanical characteristics of the cloth.
The time for heating in the temperature-holding step through the thermal pressing step is preferably selected from 5 seconds through 120 seconds. In many kinds of the cloth, the moisture contained therein can be reduced to the value given above within 5 secondsxcx9c120 seconds if the cloth is heated at a temperature for bonding the interlining-cloth or at a temperature higher by 10xc2x0 C. Therefore, by controlling the heating time within the above range, moisture contents in the temperature-holding step through the thermal pressing step can be controlled accurately. Further, most kinds of the cloth can be successfully treated in the above range. Since moisture is added in the moisture controlling step, uniform temperature is maintained even if the heating time becomes slightly long, allowing the entire cloth to be heated to a uniform temperature. It should be noted here that this heating time, too, should preferably be longer than the heating time used in bonding the interlining cloth.
A forced cooling step may be performed after the thermal pressing step. By performing the forced cooling step, the effect in the thermal pressing step can be assured more reliably. In the above forced cooling step, it is preferable again, that the cooling is performed while the cloth is supported on a belt running horizontally, so as to avoid a situation in which the cloth is cooled under stress for example. The forced cooling step can be achieved by passing room-temperature air or cooled air through the cloth.
In the stabilizing method according to the present invention, characteristics of the cloth are not significantly deteriorated since the moisture content of the cloth is controlled before the heating operation is performed. Further, since the moisture is added before the heating operation, the entire cloth can be heated uniformly by utilizing the high-temperature steam generated. Therefore, it becomes possible to perform accurate heating operation, making the method applicable even to a cloth weak in heat resistance.
An apparatus for stabilizing a cloth for achieving the above method for stabilizing a cloth comprises transporting means for transporting the cloth while supporting the cloth on a belt running horizontally, moisture controlling means for adding water to the cloth being transported by the transporting means, and thermal pressing means for thermally pressing the cloth being transported by the transporting means.
The transporting means is provided for transporting the cloth while performing treatment at each of the means, and includes a belt which runs horizontally, so as not to cause tension to the cloth.
The moisture controlling means can be a steam spraying device or a water spraying device for example. The steam spraying device can be constituted easily by using a steam generator such as a boiler. Further, combination with the conventional sponging treatment apparatus may be made. In such a case, the moisture controlling means should be capable of drying or moistening the cloth to a predetermined moisture content at a last stage of the sponging treatment apparatus.
The thermal pressing means applies pressure to the cloth under heat, and is constituted so as to apply pressure while the cloth is at a predetermined temperature. The thermal pressing means can be a heatable pressing roller in which the roller itself is heated. Alternatively, combination of a heater to heat the cloth and a roller to press the cloth may be used as the thermal pressing means.
Separate from the thermal pressing means, a temperature-holding means for heating the cloth to and maintaining the temperature of the cloth at a predetermined level may be provided, so that the cloth can be sufficiently heated before performing the pressing operation.
It is desirable to provide a forced cooling means for forcibly cooling the cloth after the thermal pressing step. A constitution for this can be to pass room-temperature air or cooled air through the cloth, thereby forcibly cooling the cloth.
As a configuration of the cloth stabilizing apparatus, there may be a moisture controlling region provided with the moisture controlling means, a temperature-holding region in which the heating means heats and maintains the cloth at a temperature, a thermal pressing operation region in which the pressing operation is performed by the pressing means to the cloth heated and maintained at the temperature, and a forced cooling region in which the cooling means forcibly cools the cloth; and the transporting means transports the cloth sequentially to each of the regions.
The stabilizing apparatus is provided with regions in which one of the steps according to the present invention is performed, and the cloth is transported between these regions by the transporting means.
It is desirable that the transporting means supports and transports the cloth on a belt so as not to cause tension to the cloth.
Further, the transporting means may not be a single device, but may be combination of a plurality of belt mechanisms.
As the transporting means in the temperature-holding region through the thermal pressing operation region, a set of transporting belts sandwiching the cloth from above and below, and made of material not permeable by steam can be used. The sandwiching belt, working with the heating means and the pressing means, can maintain the cloth at a predetermined temperature and a predetermined pressure. The sandwiching belts transport the cloth by sandwiching the cloth from above and below in the temperature-holding region, promoting the release of the residual strain of the cloth without applying extra force to the cloth, and to increase the dimensional stability.
In order to make use of the steam generated from the cloth for steaming operation thereby heating the entire cloth uniformly, it is desirable that the sandwiching belts be made of material not permeable by steam. Although a certain amount of the steam will transpire from both sides of the sandwiching belts, the amount of transpiration can be limited, and therefore it is possible to heat and maintain the temperature under a uniform condition without rapidly decreasing the water content of the cloth. Further, since the cloth is transported generally in a flat plane, being supported by the upper and lower sandwiching belts, there is no possibility for the cloth to develop flaw such as bend.
The heating means is not limited by the electric heater, but may be an electromagnetic heating device for example.
As the thermal pressing means, a set of pressing rollers sandwiching the sandwiching belts may be used. The pressing rollers apply pressure to the cloth via the sandwiching belts, making certain the stabilization of the cloth. Further, it is possible to remove wrinkles etc., as well as to smoothen the surfaces of the cloth. There is no special limitation to a construction etc. of the pressing rollers as long as the rollers are capable of performing the pressing operation at the maintained temperature. There is no specific limitation either to the number of rollers, and a plurality of pressing rollers disposed continuously along the sandwiching belts may be provided.
As the thermal pressing means, a pair of upper and lower pressing plates sandwiching the sandwiching belts for applying pressure via the sandwiching belts can be used. By using the pressing plates, it becomes possible to press the cloth uniformly over a wide area. This makes possible to reliably obtain the thermal treatment effect without deteriorating the texture of the cloth.
Further, the pressing means may be constituted so as to continuously increase the pressure in a transporting direction of the cloth. By continuously increasing the pressure, the pressing operation can be performed without applying excessive force to the cloth or without causing unnecessary deformation in the cloth. Further, even if the cloth is transported at a high speed, the pressure can be applied stably.
Further, in the moisture controlling step, the cloth stretches and/or shrinks when added with water. This stretching and/or shrinking can develop stress between the cloth and the supporting belt etc., or develop a wrinkle in the cloth. In order to prevent this, a stretch-and-shrinkage controlling step is preferably performed after the moisture controlling step. Generally, the stretching-and-shrinking control step stretches the cloth widthwise for removal of the wrinkle etc.
Inventions according to claim 25 through claim 31 of the present application are applications of the cloth stabilizing method according to the present invention to a method for manufacturing a cloth.
Conventionally, manufacture of cloth and stabilizing treatment of the cloth are performed independently. This increases not only the number of steps but also operating cost.
The method for stabilizing a cloth according to the present invention can be applied to a wide variety of cloths, not only to a cloth to which an interlining cloth is to be thermally bonded, but also to a variety of cloths which needs dimensional stability. Further, the significant dimensional stabilization makes the cloth to be applicable to a variety of after treatments. Therefore, by including the present invention as part of manufacturing steps of the cloth, it becomes possible to manufacture and stabilize the cloth simultaneously.